This invention relates to an image pickup tube using amorphous silicon as a photoconductive layer, and particularly to an image pickup tube with greatly improved life characteristics in attaining high resolution.
An image pickup tube using amorphous silicon containing hydrogen (hereinafter abbreviated as "a-Si:H") as a photoconductive layer has high photo-sensitivity, low lag and excellent thermal stability, and can be used for various purposes.
Examples of such an image pickup tube are disclosed in U.S. Pat. No. 4,255,686, British Pat. No. 1,349,351, or U.S. patent application Ser. No. 491,921. The general constitution of an image pickup tube is disclosed in U.S. Pat. No. 4,363,996, etc.
One example of conventional image pickup tubes is shown in FIG. 1.
It comprises a beam current control section 1 and a main lens section 2. These sections comprise a thermoionic cathode 3, a first grid 4, a second grid 5, a beam disc 6, cylindrical electrodes 7, 8 and 9, a mesh electrode 10, and a photoconductive layer 11.
The operation of this image pickup tube is as follows. By irradiation of the photoconductive layer 11 with light, a certain information content is produced in proportion to the intensity of the light. This information content is outputed by scanning an electron beam from the thermoionic cathode 3 toward the photoconductive layer 11 by means of other electrodes.
The thus output information content is converted into desired signals by passing it through a predetermined circuit and is imaged, for example, on television.